cros-kernel2: s/CROS_KERNEL_FAMILY/CHROMEOS_KERNEL_FAMILY/

Renaming for being consistent with other kernel vars.

BUG=None
TEST=Build kernel successfully

Cq-Depend: chromium:3488680, chromium:3488681
Change-Id: I2d47df6feaa6e5c57c0852deae5479872986423b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/3485599
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Vineeth Pillai <vineethrp@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Vineeth Pillai <vineethrp@google.com>
3 files changed